In message <2686.956200932@coconut.itojun.org>itojun@iijlab.net writes
>
>>> since we ship userland in binary form, we need to always
>>> enable IPv6 for userland (otherwise, users would need to
>>> recompile the whole userland when he turns on IPv6).
>>btw, since now sys_init tries to open v6 sockets and exits if failed
>>to open it, the binary won't work on v4 only kernel.
>
> i see, i'll try to fix it.
... how about a polic that we test IPv6-related changes on an
IPv4-only machine, before committing them? To make sure we don't
inabvertently commit changes which don't work in an IPv4-only environment?
(And the reverse for ipv6, perhaps?)